The present invention relates to electrical-connector systems. More specifically, the invention is directed to electrical-connector systems that minimize cross-talk.
Cross-talk occurs when electrical signals are transmitted through an electrical connector. More particularly, the transmission of electrical signals through a conductor of an electrical connector induces a voltage across other conductors within the same connector. This induced voltage is commonly referred to as cross-talk.
Cross-talk within contemporary electrical connectors must be controlled to be within increasingly stringent standards. Factors such as the ongoing miniaturization of electrical connectors and increases in the operating speeds of electronic systems necessitate greater control of cross-talk. For example, ANSI/EIA/TIA/568A Category-5 requirements limit pair-to-pair near (next)-end cross-talk to xe2x88x9240 dB at 100 Mhz.
Various methods and devices have been developed to reduce cross-talk in electrical connectors. For example, U.S. Pat. No. 5,562,479 describes an electrical connector in which conductors within the connector are disposed in side-by-side alignment over a predetermined distance. This arrangement causes cross-talk from one conductor to be offset by cross-talk produced in a mating portion of the connector.
Another cross-talk reduction technique is described in co-pending U.S. patent application Ser. No. 09/353,184, filed Jul. 14, 1999 and titled xe2x80x9cElectrical Connector System with Cross-Talk Compensation,xe2x80x9d which is incorporated herein by reference in its entirety. This application discloses a technique by which cross-talk is produced through a particular pattern of conductor traces formed in a circuit substrate. The cross-talk produced in the substrate offsets cross-talk that is produced within an electrical connector mounted on the substrate.
The above-noted techniques have proven effective at reducing cross-talk in electrical-connector systems. The need to accommodate cross-talk compensation circuitry within the connector or the connector substrate, however, limits the extent to which connector systems that utilize these techniques can be miniaturized. Hence, a need currently exists for an electrical-connector system that produces suitable levels of cross-talk while occupying a minimal amount of area on a circuit substrate.
A presently-preferred embodiment of an electrical-connector system comprises an electrical connector. The electrical connector comprises a plurality of upper signal contacts arranged in at least two rows of vertically-aligned pairs. The electrical connector also comprises a plurality of upper tails. Each of the upper tails has a first end electrically coupled to a respective upper signal contact. Each of the upper tails also has a second end electrically coupled to a circuit substrate. The upper tails each have a predetermined length and are spaced apart by one or more predetermined distances so that the upper tails produce a first compensating cross-talk. The first compensating cross-talk offsets an unwanted cross-talk produced by the upper signal contacts.
The electrical connector also comprises a plurality of lower signal contacts electrically coupled to the substrate. The lower signal contacts are aligned with the upper signal contacts so that the lower signal contacts are substantially located between the upper signal contacts and the circuit substrate.
One particular embodiment of the electrical-connector system further comprises the circuit substrate. The circuit substrate has a plurality of layers. At least a first, a second, and a third trace are formed on the substrate. Each of the first, second, and third traces are electrically coupled to a respective lower signal contact. In addition, the first trace includes a first portion on at least one of the plurality of layers and adjacent a portion of the second trace to produce a second compensating cross-talk. The first trace also includes a second portion on at least one of the plurality of layers and adjacent a portion of the third trace to produce a third compensating cross-talk. The second and the third compensating cross-talks offset an unwanted cross-talk between the lower signal contacts.
Further in accordance with the above-noted object, a presently-preferred embodiment of an electrical connector adapted to engage a circuit substrate comprises an upper connector portion. The upper connector portion comprises a plurality of upper signal contacts arranged in at least two rows of vertically-aligned pairs. The upper connector portion also comprises a plurality of tails each having a pre-determined length. Each of the vertically-aligned pairs of upper signal contacts is electrically coupled to a respective first and second tail. The first and the second tails are positioned substantially side-by-side. The plurality of tails are substantially co-planar and are spaced apart by one or more pre-determined distances so that the tails produce a compensating cross-talk that offsets an unwanted cross-talk produced by the upper signal contacts.
The electrical connector also comprises a lower connector portion that is substantially aligned with the upper connector portion so that the lower connector portion is substantially located between the upper connector portion and the circuit substrate.
A further object of the present invention is to provide method of reducing cross-talk in an electrical-connector system mounted to a circuit substrate. In accordance with this object, a presently-preferred method of reducing cross-talk in an electrical-connector system mounted to a circuit substrate comprises the step of providing an electrical-connector system having a lower electrical connector and a stacked, upper electrical connector, each electrical connector including contacts with tails and producing an unwanted cross-talk. The method also comprises the steps of providing a circuit substrate to receive the tails, and producing a compensating cross-talk in the tails of the contacts of the upper connector to reduce the unwanted cross-talk of the upper connector. The method further comprises the step of producing a compensating cross-talk in the circuit substrate to reduce the unwanted cross-talk of the lower connector.